[ntp:questions] NTP 4.2.2p4 loopstats

TomD Thomas.Donovan at gmail.com
Mon Nov 13 20:51:33 UTC 2006


re: "the clock discipline jitter has been separated from the selection
& "loopstats have not changed in many years"
& "This is the same data reported over two decades"

No problem with separating the two jitters - but it was a surprise that
the loopstats jitter field  switched to reporting only the new
clock_jitter, rather than continuing to report sys_jitter starting with
NTP 4.2.2.

clock_jitter appears to be a 3rd derivative vs. sys_jitter which
appears to be a 2nd derivative of the clock offset.  Is that correct?

Graphing the jitter value from loopstats shows a much smaller value
starting with 4.2.2.  It doesn't correspond clearly to real-world
things like network load, as it did before the change. (although I
haven't collected enough of the new 'jitter' values to be sure of this)


p.s. This topic seems to have gotten out of hand.  The original
question was "did jitter in loopstats change" and "what's a simple
definition of the new value".

Well, at least we've answered jg's first question:  'Yes, but the old
value is still available with a small code change.'

I'm a little taken aback by all the other things this topic has
meandered into: e.g. *what values ntpq displays, *what it calls them,
*the ntpq op command,  *the ntpq opeers value (bug 666), *ntpdc,
*ntp.isc->udel download links, *the other loopstats fields, *projects
to design new analysis mechanisms, etc. etc. etc.  Yikes!

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